<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.transitionbox{
				width: 20px;
				height: 20px;
				background-color:red;				
				position: relative;
				/* transition: height 2s; */
				transition: height 2s;
			}
			.transitionbox:hover{
				/* width: 400px; */				
				height: 200px;
			}
		</style>
	</head>
	<body>
		<h3>拉伸盒子动画效果</h3>
		<h5>transition它有两个参数 拉伸方向width 2s动画
		执行时间</h5>
		<div class="transitionbox"></div>
	</body>
</html>

